This is an article outlining the steps for collecting network logs.
Wireshark and Netsh: See the KB - How to Get a Wireshark Trace?.
Fiddler is a web debugging proxy tool that can capture HTTP(S) traffic. It can only run on Windows.
- Download Fiddler.
- Open it.
- Clear your browser cache.
- Browse to your site. Visit the pages that are problematic and a contrasting non-problematic page if appropriate, for contrast.
- Important: Fiddler can capture local traffic by Using The Machine's Name As The Host Name rather than 'localhost'.
- Click File > Save > All Sessions....
- Attach the resulting file in .saz format for Support.
For gathering browser network logs (needed for our cloud tickets), see the KB - How To Generate HAR File? .